Liquid crystals

Claim 2

A compound of the formula: ##STR22## wherein R 1 is hydrogen or straight-chain alkyl; R 2 is --CN, --R, --COR, --COOR or when R 2 is positioned on an aromatic ring R 2 also can be --OR, --OOCR or --F; R is alkyl; A is a group with 1 to 4 six-membered rings, A and B rings being linked directly with one another, and rings A in each case being linked via a single covalent bond or being linked at one or two positions also via --COO--, --OOC-- or --CH 2 CH 2 --; the six-membered rings in A and ring B each are 1,4-phenylene or trans-1,4-cyclohexylene, with the proviso that a maximum of two adjacent trans-1,4-cyclohexylene rings are linked directly via a single covalent bond; and m is the integer 2, or when ring B is trans-1,4-cyclohexylene, m also can be the integer 0.

Claim 3

The compound of the claim 1, wherein the compound has the formula: ##STR23## wherein rings B, C and D each are 1,4-phenylene or trans-1,4-cyclohexylene X 1 is a single covalent bond and X 2 is --COO--, --OOC--, --CH 2 CH 2 --, or when at least one of the rings B, C and D is not trans-1,4-cyclohexylene, X 2 also can be a single covalent bond; n is the integer 0 or 1; and R 1 , R 2 , R and m have the significances given in claim 1.

Claim 4

The compound of claim 1, wherein ring B is trans-1,4-cyclohexylene.

Claim 5

The compound of claim 1, wherein the compound has the formula: ##STR24## wherein each of rings B 1 and B 2 is 1,4-phenylene or trans-1,4-cyclohexylene; X 1 is a single covalent bond and X 2 is --COO--, --OOC--, --CH 2 CH 2 --, or when at least one of the rings B 1 and B 2 is not trans-1,4-cyclohexylene, X 2 also can be a single covalent bond; n is the integer 0 or 1; and R 1 , R 2 , R and m have the significances given in claim 1.

Claim 6

The compound of claim 4, wherein X 1 is a single covalent bond; X 2 is a single covalent bond; and each of rings B 1 and B 2 is 1,4-phenylene.

Claim 7

The compound of claim 2, wherein n is the integer 0.

Claim 8

The compound of claim 1, wherein R is straight-chain C 1 -C 12 -alkyl.

Claim 9

The compound of claim 1, wherein R 2 is cyano, alkyl, or when R 2 is positioned on an aromatic ring R 2 also can be alkoxy.

Claim 10

The compound of claim 8, wherein R 2 is cyano, C 3 -C 7 -alkyl, or when R 2 is positioned on an aromatic ring R 2 also can be C 2 -C 6 -alkoxy.

Claim 11

The compound of claim 1, wherein R 1 is hydrogen or straight-chain C 1 -C 10 -alkyl, and m is the integer 0.

Claim 12

The compound of claim 1, wherein R 1 is hydrogen or straight-chain C 1 -C 8 -alkyl, m is the integer 2.

Claim 13

The compound of claim 10, wherein R 1 is hydrogen or straight-chain C 1 -C 5 -alkyl, and m is the integer 0.

Claim 14

The compound of claim 11, wherein R 1 is hydrogen or straight-chain C 1 -C 3 -alkyl, and m is the integer 2.

Claim 15

The compound of claim 1, wherein the compound has the formula: ##STR25## wherein each of rings B 1 , B 2 , B 3 and B 4 is 1,4-phenylene or trans-1,4-cyclohexylene; n is the integer 0 or 1; X 1 is a single covalent bond and each of X 2 , X 3 and X 4 is a single covalent bond, --COO--, --OOC-- or --CH 2 CH 2 --, with the proviso that a maximum of two adjacent trans-1,4-cyclohexylene rings are linked directly via a single covalent bond; and R 1 , R 2 , R and m have the significances given in claim 1.

Claim 16

The compound of claim 14, wherein m is the integer 0.

Claim 17

A liquid crystalline mixture comprising at least two components, wherein at least one component is a compound of the formula: ##STR26## wherein R 1 is hydrogen or straight-chain alkyl; R 2 is --CN, --R, --COR, --COOR or when R 2 is positioned on an aromatic ring R 2 also can be --OR, --OOCR or --F; R is alkyl; A is a group with 1 to 4 six-membered rings, A and B rings being linked directly with one another, and with rings A in each case being linked via a single covalent bond or being linked at one or two positions also via --COO--, --OOC-- or --CH 2 CH 2 --; the six-membered rings in A and ring B each are 1,4-phenylene or trans-1,4-cyclohexylene, with the proviso that a maximum of two adjacent trans-1,4-cyclohexylene rings are linked directly via a single covalent bond; and m is the integer 2, or when ring B is trans-1,4-cyclohexylene, m also can be the integer 0.

Claim 18

A liquid crystalline mixture comprising at least two components, wherein at least one component is a compound of the formula: ##STR26## wherein R 1 is hydrogen or straight-chain alkyl; R 2 is --CN, --R, --COR, --COOR or when R 2 is positioned on an aromatic ring R 2 also can be --OR, --OOCR or --F; R is alkyl; A is a group with 1 to 4 six-membered rings, A and B rings being linked directly with one another, and with rings A in each case being linked via a single covalent bond or being linked at one or two positions also via --COO--, --OOC-- or --CH 2 CH 2 --; the six-membered rings in A and ring B each are 1,4-phenylene or trans-1,4-cyclohexylene, with the proviso that a maximum of two adjacent trans-1,4-cyclohexylene rings are linked directly via a single covalent bond; and m is the integer 2, or when ring B is trans-1,4-cyclohexylene, m also can be the integer 0.

Claim 19

The liquid crystalline mixture of claim 16, wherein the other component is one or more compounds selected from the group consisting of: ##STR27## wherein ring B 1 is 1,4-phenylene or trans-1,4-cyclohexylene; R 9 is straight-chain C 2 -C 7 -alkyl; R 10 is cyano or straight-chain C 1 -C 6 -alkoxy, R 11 is cyano, straight-chain C 1 -C 7 -alkyl or C 1 -C 7 -alkoxy; each of R 12 and R 13 is straight-chain C 1 -C 7 -alkyl; p is the integer 0 or 1; R 14 is trans-4-alkylcyclohexyl, 4'-alkyl-4-biphenylyl, p-(trans-4-alkylcyclohexyl)phenyl, 2-(trans-4-alkylcyclohexyl)ethyl or p-[2-(trans-4-alkylcyclohexyl)ethyl]phenyl and R 15 is trans-4-alkylcyclohexyl; or R 14 is trans-4-alkylcyclohexyl and R 15 is p-(trans-4-alkylcyclohexyl)phenyl, p-[2-(trans-4-alkylcyclohexyl)ethyl]phenyl or 4'-(trans-4-alkyl-cyclohexyl)-4-biphenylyl; or R 14 is p-alkylphenyl and R 15 is p-[2-(trans-4-alkylcyclohexyl)ethyl]phenyl; each of the alkyl groups in R 14 and R 15 is straight-chain C 1 -C 7 -alkyl; one of Z 1 and Z 2 is --COO-- or --OOC-- and the other as well as each of Z 3 and Z 4 are single covalent bonds or one of Z 1 , Z 2 , Z 3 and Z 4 also can be --CH 2 CH 2 --; each of rings B 1 and B 5 in formula XCI is a group of the formula ##STR28## or trans-1,4-cyclohexylene; each of rings B 2 , B 3 and B 4 is a group of formula XCII, or when rings B 2 , B 3 and B 4 are not linked with at least one of the other two of these rings by a single covalent bond, rings B 2 , B 3 and B 4 also can be trans-1,4-cyclohexylene; Y is hydrogen or when Y is positioned on one of the rings of formula XCII which is not linked with a further ring via a single covalent bond, Y also can be fluorine, chlorine or methyl; each of R 16 and R 17 is straight-chain C 1 -C 7 -alkyl or when positioned on a ring of formula XCII R 16 and R 17 also can be straight-chain C 1 -C 7 -alkoxy.

Claim 20

The liquid crystalline mixture of claim 16, wherein the other component is a compound of the formula: ##STR29## wherein R 8 is straight-chain C 1 -C 12 alkyl.

Claim 21

An electro-optical cell comprising: (a) two plate means; (b) liquid crystal means disposed between the two plate means and including a compound of the formula: ##STR30## wherein R 1 is hydrogen or straight-chain alkyl; R 2 is --CN, --R, --COR, --COOR or when R 2 is positioned on an aromatic ring R 2 also can be --OR, --OOCR or --F; R is alkyl; A is a group with 1 to 4 six-membered rings, A and B rings being linked directly with one another, and rings A in each case being linked via a single covalent bond or being linked at one or two positions also via --COO--, --OOC-- or --CH 2 CH 2 --; the six-membered rings in A and ring B each are 1,4-phenylene or trans-1,4-cyclohexylene, with the proviso that a maximum of two adjacent trans-1,4-cyclohexylene rings are linked directly via a single covalent bond; and m is the integer 2, or when ring B is trans-1,4-cyclohexylene, m also can be the integer 0; and (c) means for applying an electrical potential to said plate means.

Claim 22

An electro-optical cell comprising: (a) two plate means; (b) liquid crystal means disposed between the two plate means and including a compound of the formula: ##STR30## wherein R 1 is hydrogen or straight-chain alkyl; R 2 is --CN, --R, --COR, --COOR or when R 2 is positioned on an aromatic ring R 2 also can be --OR, --OOCR or --F; R is alkyl; A is a group with 1 to 4 six-membered rings, A and B rings being linked directly with one another, and rings A in each case being linked via a single covalent bond or being linked at one or two positions also via --COO--, --OOC-- or --CH 2 CH 2 --; the six-membered rings in A and ring B each are 1,4-phenylene or trans-1,4-cyclohexylene, with the proviso that a maximum of two adjacent trans-1,4-cyclohexylene rings are linked directly via a single covalent bond; and m is the integer 2, or when ring B is trans-1,4-cyclohexylene, m also can be the integer 0; and (c) means for applying an electrical potential to said plate means.

Claim 23

The compound of claim 1, p-[trans-4-(trans-1-propenyl)cyclohexyl]benzonitrile.

Claim 24

The compound of claim 1, p-[trans-4-(trans-1-butenyl)cyclohexyl]benzonitrile.

Claim 25

The compound of claim 1, p-[trans-4-(trans-1-pentenyl)cyclohexyl]benzonitrile.

Claim 26

The compound of claim 1, p-[trans-4-(3-butenyl)cyclohexyl]benzonitrile.

Claim 27

The compound of claim 1, p-[trans-4-(trans-3-pentenyl)cyclohexyl]benzonitrile.